This invention relates to a dispensing nozzle of the type used for dispensing gasoline or the like. Gasoline dispensing nozzles conventionally include a casing having an inlet, an outlet spout, and a poppet valve for controlling flow between the inlet and outlet spout. The poppet includes a sealing disk for shutting off flow when the valve is closed and a depending tapered skirt for modulating the flow through its associated valve seat as the poppet is raised and lowered. The poppet is urged downwardly against its seat by a spring. A valve stem, which is operated by a manually operated lever or handle, extends into the poppet valve and opens the poppet valve against the force of the spring. An automatic shut-off assembly forms a pivot for the lever; when the tip of the spout is submerged, the shut-off assembly shifts the pivot point and prevents the lever from moving the valve stem. This construction is well known in the art and is described in my U.S. Pat. No. 3,757,834 and in Lawrence et al, U.S. Pat. No. 3,877,480, for example.
Presently known gasoline dispensing nozzles were designed to enable the user to stop flow "on the penny". Unfortunately, the quantity of gasoline represented by that penny has become so small that these nozzles are no longer able to provide that kind of control, because they can not handle such extremely low flow rates. Moreover, the nozzles are now frequently used on self-service gasoline pumps, and the persons using them are not generally highly skilled at the delicate operation of the nozzle. As a result, most self-service customers tend to overshoot the amount of gasoline they intend to put into their gasoline tanks by a penny or two, and the service station tends to round off the charge to the lower amount. Over the course of time, the cumulative loss to the service station can be quite substantial.
Several attempts have been made to modify existing gasoline dispensing nozzles to provide better low-flow characteristics.
One approach has been to change the casting and poppet to provide a smaller cross-section to the opening defined by the valve seat. This approach does not greatly improve the low-flow characteristics, and instead merely reduces the available high-flow rate.
Another approach has been to modify the shape of the poppet valve skirt to provide a greater difference between the diameter of the upper part of the skirt, for controlling low flow, and the diameter of the lower part of the skirt, for controlling high flow. This approach requires maintaining close tolerances in both the size of the poppet skirt and the size of the valve seat, and has also not been very effective.
Another approach has been to modify the valve stem. By reducing the diameter of the upper end of the stem, thereby creating a shoulder on the stem, a plastic sleeve has been mounted on the upper end of the stem. This sleeve carries a small wing which engages a lower face of the poppet. As the stem is raised by the manual lever, the wing lifts one side of the poppet. This design has been used in a nozzle produced by Emco Wheaton Inc. of Conneaut, Ohio (the general form of which is shown in Billian, U.S. Pat. No. 3,196,908), but it is not applicable to more common gasoline dispensing nozzles, such as the nozzle commonly designated as a type "1A", illustrated in Lawrence et al, U.S. Pat. No. 3,877,480, for example.